On Thursday, Hamas leaders claimed success in the month-long campaign, which began on March 12, for collaborators to turn themselves in as a means of being granted leniency.

"The campaign to combat espionage achieved a number of goals, and from this evening the deadline for Israeli collaborators to turn themselves in has ended," said interior ministry spokesman Islam Shahwan, according to AFP.

"Successes were achieved," he said, adding that the number of people now believed to be working on behalf of Israel was "low."

Shahwan said that some people had surrendered during the amnesty but did not give details on their likely treatment.

Under Palestinian Authority law, collaboration with Israel, including sharing information on planned terrorist attacks, is punishable by death.

All executions must be approved by the PA chairman before they can be carried out, but Hamas no longer recognizes the legitimacy of incumbent Mahmoud Abbas, whose four-year term ended in 2009.

A Gaza official said that five or six suspects fled to Israel before they could be apprehended.

During the recent November conflict, at least seven people were gunned down by Hamas after being accused of being collaborators.

The bodies of six were dragged behind vehicles through the streets of Gaza City.

The killings were claimed by Hamas militants from the Ezzedine al-Qassam Brigades in notes pinned to their bodies, which accused them of being traitors.

New York-based Human Rights Watch criticized the terror organization on Thursday for failing to investigate the killings.

"Hamas's inability or unwillingness to investigate the brazen murders of seven men makes a mockery of its claims that it is upholding the rule of law in Gaza," HRW's Middle East director Sarah Leah Whitson said in a statement.

The Islamist movement is blacklisted as a terror group by both the European Union and the United States.